First Month with "lasering " Trials and triumphs

Hi All,

Im slowly getting the hang of things with lasering coming from a cnc Mach3 background and there are a few things that seem to be learned by trial and error …lots of error .
There has been lots of good info here that has been very helpful but some things were less obvious .
Perhaps I can offer some thing back .

The first thing that had me stumped was that many machines/controllers came with $1 set to other than 255. This means that whenever there is no movement there is nothing to stop the gantries from creeping one way or the other resulting in the machine being off calibration and impossible to rely on .

Changing it to 255 keeps current on the motors ,locking them and preventing any movement . I cant work out why one would ever not want holding torque to keep the calibration true as just a slight breeze or tension from cable bundles always is at play .
I would be grateful if somebody could explain to me why you would not want holding torque.
There must be a reason as it is usually off by default.
This is really fundamental for repeatability .

Another thing that seems to not get much attention is air assist smoothing .
Most of the small aquarium pumps we use , pulse the air making noise and vibration exactly where you don’t want it .

Running the air into, and out of a plastic 5 litre container smooths out the air flow and almost completely eliminates the noise . Its like a capacitor but air based.
Just drill 2 holes in the plastic cap and force the hoses into the holes making an air tight seal .
This is low pressure air so easy to do.
Now you have a constant and quiet hissing sound which is easier to direct with a DIY nozzle.

One other thing that has been and still is frustrating is how grbl can be left in a state / Mode that can be confusing as depending on the mode that it was left in can give unexpected actions . Different programs can leave grbl in different states which I am just beginning to understand . lots of resets and re homing seem to do the trick ,this still catches me out as I dont fully understand exactly why this is the case.


IMO, this boils down to the “cargo cult” mentality around configurations: if those settings worked for that guy over there, surely they will work for me! But, while tweaking $21 to set the hard limits, that guy made a simple typo and clobbered $1. The configuration migrated to somebody else with “the same machine” who changed other values, and eventually you’ll find the whole mess as solid recommendations somewhere on the Interwebs.

Bonus reason: it keeps the steppers cooler after that guy cranked the stepper drivers to some absurdly high current. Hey, it works for him!

Your air assist buffer is a good idea. The air pump in my CO₂ laser also pulses, but after the air goes through all the tubing / solenoids / valves / meters inside the cabinet it comes out as a nice, smooth wind at the nozzle. Now, you might wonder why they’d put the pump inside the cabinet where it inhales the fumes, but obviously you and I think too much:

Keep on thinking!

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